Lewis Cass was born in Exeter, New Hampshire, on October 9, 1782. He received his formal schooling at the Exeter Academy, before moving with his parents to Wilmington, Delaware, in 1799. Cass briefly earned a living as a schoolteacher, before moving to the Northwest Territory in 1801. Purchasing a farm near Zanesville, Ohio, Cass preferred a legal career to life as a farmer.
Cass quickly became an important political figure in the new state of Ohio. He was elected to the Ohio House of Representatives in 1806 and also served as a United States marshal for the Ohio district from 1807 to 1812. He resigned as U.S. marshal in 1812 to enlist in the United States Army. He played an active role in Ohio's defense during the War of 1812. Cass began the war as a colonel under General William Hull. He was present when Hull surrendered Detroit in 1812. Cass quickly moved up the ranks, however, attaining the rank of brigadier general by the war's conclusion.
During the War of 1812, President James Madison appointed Cass the governor of the Michigan Territory. He served in this position from 1813 to 1831. President Andrew Jackson appointed Cass Secretary of War in 1831. Cass held this position until 1836, when Jackson appointed him the United States' ambassador to France. Cass remained in France until 1842. He returned to Michigan and was elected to the United States Senate from that state in 1845. He strongly supported United States expansion and rallied behind President James K. Polk during the U.S.-Mexican War. Cass firmly believed that incorporating new people and territory under United States control would help these people live more fruitful lives. This belief was a major component of Manifest Destiny. Like Cass, many Americans during the 1840s believed that God wanted the Americans to expand -- that it was the United States' God-given destiny.
By 1848, Cass had become one of the most well-known citizens of the United States. That same year, the Democratic Party selected him to be its candidate for President of the United States. The Democrats hoped that Cass would be attractive to a wide variety of Americans because of his views on slavery. Cass advocated popular sovereignty. Under popular sovereignty, the people residing in a territory would decide whether or not their state would allow slavery. While some Americans supported this position, many other people feared that it was too vague. Over the past thirty years, both the North and South had tried to maintain the same number of free and slave states. By maintaining a balance between the two, both sides would have an equal number of senators in the United States government. By creating this balance, neither side would be able to submit a bill to the president to sign into law that would either outlaw slavery or make it legal everywhere. Cass's proposal, theoretically, could upset this balance. Primarily for this reason, Cass lost the presidency to Zachary Taylor, a hero from the Mexican War and a man who refused to state his views on practically any of the issues raised during the campaign, including slavery. Cass did win his former home state of Ohio, but many Ohioans found him unacceptable, including abolitionists.
Following Cass's loss in the election of 1848, he returned to Michigan and continued to serve as one of that state's U.S. Senators. He held his Senate seat until 1857, when he became President James Buchanan's Secretary of State. He resigned this position in 1860 and retired to Detroit, dying there on June 17, 1866.